Improved Method for Inoculation of a Cell Suspension Into a Hollow Fiber Bioreactor

Abstract

Monoclonal antibody (MAb) production was evaluated with three different murine hybridoma cell lines in a “mini” hollow fiber bioreactor. Optimized production rates between 17–25 mg/day could be achieved with medium consumption of 2 liters per week. Antibody product was harvested at 3–4 mg/ml up to five times per week. Bioreactor productivity was enhanced twofold when cartridges were inoculated by direct ultrafiltration of cells in their conditioned medium as opposed to centrifugation, resuspension and inoculation in a smaller volume of fresh medium. Control reactors were started by centrifuging 2–2.5 x 10⁸ cells and resuspending in 3 ml of fresh medium with 5–25% fetal bovine serum (FBS) prior to inoculation into the 7 ml extracapillary space (ECS) of the bioreactor. Alternatively, the same total number of cells were inoculated into the ECS directly from up to 100 ml of conditioned medium by ultrafiltration. The twenty to sixty minute ultrafiltration procedure concentrates various serum and cellular growth factors and potentially better distributes the cells around the fibers. It resulted in the decrease of the lag phase from twelve to sixteen days to three to six days and surprisingly, increased rates of monoclonal antibody production throughout the course of runs of up to sixty days duration.